Unless otherwise indicated herein, the description in this background section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
In typical color output devices, such as printers and monitors, reproducibility of a color range is device-dependent. Hence, a target exhibiting an original color may be reproduced in different colors on different devices.
Therefore, color-space compression has been used to correct a color value by compressing a color space having a color range, in a process known as gamut mapping.
For example, as illustrated in FIG. 9A, one correction method causes each color value in a color space to move relatively so as to maintain its lightness. Further, as illustrated in FIG. 9B, a second correction method maintains a chroma balance while moving a color value in a color space.
Incidentally, color reproducibility on an object-by-object basis is not taken into consideration even by those methods for color space compression. Therefore, in a case of outputting a specific graphic form whose color is strictly defined such as a logo mark and a design mark of a company, it is not possible to reproduce the color with accuracy.
A typical color printing apparatus performs color correction by using a color correction function defined for each object based on an attribute (e.g. such as raster, vector, and text) of the object interpreted from print data.
According to the typical color printing apparatus, the same color correction is performed uniformly for each object, and hence if an image including a logo mark as a graphic form is subjected to the color correction suitable for the logo mark, other graphic forms than the logo mark are also subjected to the same color correction.
Further, a typical image processing apparatus substitutes a specific color with a special color, while subjecting colors other than the specific color to normal color conversion.
According to the typical image processing apparatus, each pixel is converted into the same color uniformly, and hence if the color of the logo mark is set as the specific color, other pixels formed of the specific color are also substituted by the same color.